Sneaky Contrast Adjustments
Flattening a curve is usually harmful to an image because the detail in the area you are adjusting will be very difficult to see. You can often cheat, however, by analyzing the histogram to determine which areas of your image won't be harmed by flattening the curve. Because short lines in a histogram indicate shades that are not very prevalent in the image, those areas can often be flattened in a curve without noticeable degradation to the image. Flattening one part of the curve will allow you to make the rest of the curve steeper, which will increase the contrast of those areas and make the area appear to have more detail.
Here's how it works: While you're in the Curves dialog box, glance over at the Histogram palette ...
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